Use CloseIssue and ReopenIssue instead of ChangeStatus (#32467)

The behaviors of closing issues and reopening issues are very different.
So splitting it into two different functions makes it easier to
maintain.

- [x] Split ChangeIssueStatus into CloseIssue and ReopenIssue both at
the service layer and model layer
- [x] Rename `isClosed` to `CloseOrReopen` to make it more readable.
- [x] Add transactions for ReopenIssue and CloseIssue

---------

Co-authored-by: Zettat123 <zettat123@gmail.com>

models/issues/issue_update.go

@@ -119,8 +119,8 @@ func doChangeIssueStatus(ctx context.Context, issue *Issue, doer *user_model.Use
 	})
 }
 
-// ChangeIssueStatus changes issue status to open or closed.
-func ChangeIssueStatus(ctx context.Context, issue *Issue, doer *user_model.User, isClosed bool) (*Comment, error) {
+// CloseIssue changes issue status to closed.
+func CloseIssue(ctx context.Context, issue *Issue, doer *user_model.User) (*Comment, error) {
 	if err := issue.LoadRepo(ctx); err != nil {
 		return nil, err
 	}
@@ -128,7 +128,45 @@ func ChangeIssueStatus(ctx context.Context, issue *Issue, doer *user_model.User,
 		return nil, err
 	}
 
-	return changeIssueStatus(ctx, issue, doer, isClosed, false)
+	ctx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer committer.Close()
+
+	comment, err := changeIssueStatus(ctx, issue, doer, true, false)
+	if err != nil {
+		return nil, err
+	}
+	if err := committer.Commit(); err != nil {
+		return nil, err
+	}
+	return comment, nil
+}
+
+// ReopenIssue changes issue status to open.
+func ReopenIssue(ctx context.Context, issue *Issue, doer *user_model.User) (*Comment, error) {
+	if err := issue.LoadRepo(ctx); err != nil {
+		return nil, err
+	}
+	if err := issue.LoadPoster(ctx); err != nil {
+		return nil, err
+	}
+
+	ctx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer committer.Close()
+
+	comment, err := changeIssueStatus(ctx, issue, doer, false, false)
+	if err != nil {
+		return nil, err
+	}
+	if err := committer.Commit(); err != nil {
+		return nil, err
+	}
+	return comment, nil
 }
 
 // ChangeIssueTitle changes the title of this issue, as the given user.